JPH0380985A - Apparatus for removing pollutant in liquid - Google Patents

Abstract

PURPOSE:To safely and continuously remove pollutant due to perishable foods without using a surfactant by sucking air from above under the negative pressure generated on the back surface side of a wing blade rotated in water to discharge ultrafine air bubbles. CONSTITUTION:In a aerator 4 utilized as a bubble generating means, a hollow shaft 13 having an upper disc 14, a lower disc 15 and wing plates 16 is made rotatable at a high speed. The wing plates 16 are rotated by rotating the above mentioned hollow shaft 13 in water to generate negative pressure behind the wing plates 16 and the open air is sucked through a large number of air holes 17 provided to the hollow shaft 13 to discharge ultrafine air bubbles 18 into water in large quantities. Air bubbles 15 generated at this time are dispersed by centrifugal force not only to improve the mixing with water but also to activate the adsorbing action of suspended pollutants.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a device for removing pollutants in the fields of aquaculture and fishing, transport of live fish, fish breeding, etc., and in the food industry, for example, in the treatment of wastewater in rice washing water, etc. It is.

[Prior art] In the live fish farming and transportation systems that are currently in practical use, the main purpose is to supply air, pure oxygen, etc. into the water to maintain the life of the live fish. Even if it were possible to raise them, it was difficult to maintain a sanitary water environment due to the accumulation of waste products in the water.

In particular, regarding the removal of harmful living bacteria such as Vibrio bacteria, there is no effective means for transporting or breeding live fish, and the reality is that live fish are left uncontaminated by Vibrio bacteria.

However, improvements to remove harmful bacteria and pollutants are an urgent issue from both human hygiene and fish life support perspectives.

Furthermore, the treatment of large amounts of wastewater generated in the food industry, such as rice rinse water, requires large-scale equipment using an aeration tank and a sedimentation tank, and a simpler equipment is desired.

As related to the technology of using foam to remove suspended solids in water, many examples of the use of foam as flotation methods are known. In this method, air is released into the water through an aeration tube to create bubbles, and pollutants or metals are prevented from adhering to the bubbles and floated and separated.A surfactant is used for the purpose of generating the bubbles.

However, the size of the bubbles used in the flotation method is large and unsuitable for removing harmful bacteria such as Vibrio bacteria.To date, there have been no examples of using bubbles to remove Vibrio bacteria. I can't see it.

Furthermore, it goes without saying that it is inappropriate to use surfactants to generate foam in the life support of fish and in the food industry.

[Problems to be Solved by the Invention] Accordingly, an object of the present invention is to remove pollutants such as harmful bacteria from wastewater in fields such as aquaculture, live fish transportation, and fish breeding, as well as food industry wastewater, by using foam and surface active material. It is an object of the present invention to provide a device for continuous removal without using a chemical agent.

[Means for Solving the Problems] In order to solve the above problems, the present inventors have repeatedly studied the following items.

<1> In the transport of live fish and the food industry, etc., it is not possible to add surfactants for water foaming, so it is necessary to foam into ultra-fine bubbles, and for this purpose it is necessary to select an appropriate aerator. Must be.

The aeration device (Japanese Patent Publication No. 62-34436, etc.) invented by Sato Tetsusanbe, one of the inventors of the present invention, is ideal for easily generating stable foam made of ultra-fine bubbles, so this device Make use of it.

(2) When considering the life support of fish during transport of live fish and human hygiene in live fish dishes where fish are eaten raw, it is necessary to be able to remove harmful bacteria, especially Vibrio bacteria, in environments containing water using foam.

(3) When attempting to remove bubbles continuously, it is necessary to maintain the position of the interface between the bubbles and the liquid at a substantially constant position. If you do not do this, not only the bubbles but also almost all of the water inside will be absorbed, damaging the fish, and if the situation continues for a long time without bubbles, components secreted by the fish will accumulate and have a negative effect.

Therefore, it is necessary to perform control that can deal with these problems.

(4) The device must be compact and capable of efficient foam separation.

To this end, it is necessary to take advantage of the features of the aeration device developed by the present inventors and to compensate for its shortcomings.

(5) In the treatment of waste water such as rice washing water using foam, it is necessary to have a treatment capacity that can handle even if the flow rate is increased.

As a result of intensive study on the above items, the present invention was completed.

That is, the present invention is characterized in that: 1) it is equipped with a self-suction type foam generating device that generates bubbles by introducing air into the liquid using negative pressure generated on the back surface of a rotating impeller; 2) The device for removing contaminants from the liquid according to item 1 above, which has means for controlling the liquid level; 3) The device from item 1 above, in which the liquid flows from the top to the bottom by the rotating impeller. 4) The device for removing contaminants from a liquid according to item 1 above, characterized in that the device is provided with one or more partition plates for canceling the rotational vector of bubbles.

The pollutant removal device of the present invention is an aeration device (
Hereinafter, it will be referred to as force-vous aerator. 〉 is used as a means of generating bubbles, which is one of its major features.

As shown in FIG. 2 as an example, the force-vous aerator has a hollow shaft 13 that is rotated at high speed by a motor (not shown), and has an upper disk 14, a lower disk 15, and a hollow shaft at its lower end. A vane plate 16 is attached and rotates by rotation of the shaft.

When the vane plate 16 rotates underwater, negative pressure is generated behind it, and the air from the upper part is sucked in through the numerous air holes 17 provided on the shaft in both discs at the end of the shaft, and is submerged as ultra-fine bubbles 18. released into the

The feature is that ultra-micro bubbles 18 are generated and the direction of their movement is in a horizontal plane perpendicular to the rotation axis, and the bubbles are dispersed by centrifugal force in the plane perpendicular to the rotation axis. Not only does it mix well with water, but it can also create good bubbles in a small aquarium.

Bubbles have the function of trapping suspended pollutants floating in water, and the tube is basically proportional to the surface area of the bubbles, but the smaller the bubbles are, the larger the surface area becomes. Therefore, the performance of a pollutant removal device that uses bubbles depends on how it can generate ultrafine bubbles.

On that point, Carve? The spoolator is ideal for generating large amounts of ultra-fine bubbles, and can be said to be superior to any other bubble generation mechanism.

In particular, as will be clear from the later examples, it is thought that ultrafine bubbles take in bacteria such as B. Throat bacterium in the water, and the present invention shows that by separating these bubbles, bacteria such as Vibrio bacterium can be effectively removed. This is its biggest feature.

Next, as a detailed mechanism, by detecting the interface between the bubbles and the water surface and the top surface of the bubbles, the water surface inside the pollutant removal device is always maintained at a certain appropriate height, thereby maintaining the optimum level of bubbles. . As a means of achieving this, the discharge valve was controlled.

On the other hand, although it is desirable for the foam to remove pollutants to rise steadily and quietly, the vector of rotation provided by the force aerator is detrimental to stable foam generation. In order to counteract this rotational vector, we have made improvements such as installing vertical bulkheads (baffle plates), and by increasing the amount of water that can be treated with a small tank as much as possible, we have improved its practicality. It also made it possible to treat sewage such as sewage water.

[Example] Hereinafter, the apparatus of the present invention will be explained using examples.

FIG. 1 shows an outline of a live fish tank equipped with a pollutant removal device in which sea bream was transported and tested for 48 hours after transport as an example of the present invention.

In Fig. 1, the fish tank 1 has a tank volume of 9501, is filled with seawater 8901, and contains 50 sea bream 3 (weighing approximately IKy/fish).
It rotates and releases air into the water, creating bubbles.

The motor 5 is of 400W.

Seawater 2 is pumped out of the fish tank 1 by a pump 6 and circulated within the apparatus. The foam removal duct 7 collects foam floating on the surface, and the foam is retained in a foam reservoir tank 8 and liquefied, collected in a liquefied water reservoir tank 9, and discharged to the outside of the thread by a drain valve 10.

-5 The seawater from which bubbles have been removed passes through a filter 11 and is returned to the fish tank 1 through a pipe 12. The filtration device is made of activated carbon, zeolite, mineral stone, etc. Using this device, 50 live fish (sea bream) were transported by truck to 50, and then test measurements were conducted for a total of 48 hours.

Measurements were taken of water temperature, turbidity, dissolved oxygen, and dissolved organic matter.

FIG. 3 shows the change in water quality versus the elapsed time when this force 7 aerator 4 was operated in a pollutant removal device.

The water temperature in the fish tank is approximately constant as shown by W (・)16
．． The temperature was kept at 6-17.1°C.

The pH of the fish tank water was 8.19 before the fish became adults, but it temporarily decreased twice over time, and then gradually increased and recovered to pH 7.86. The decrease in pH is thought to be caused by an increase in NO3 nitrogen concentration and an increase in CO2 concentration. The dissolved oxygen concentration (Do) (○) in the fish tank water was maintained at almost the saturated concentration (7.61 m1/J, 17°C).This is due to the supply of oxygen to the water that exceeds the oxygen consumption of the sea bream by the Carve 7 Aerator. This is due to

Dissolved organic matter (DOC>(II) in fish tank water was 6.2 mg/fJ at the beginning of the experiment, but it increased linearly at a rate of 0.7 μ/1 h until about 15 hours, and After 27 hours, the percentage decreases, and after 27 hours, it is about 0.07 mg.
/j ・h increased at a low rate. On the other hand, DO of foam liquefied water
C11 degrees (not shown) is 49.5 my in the first 6 hours.
/j, but reached a high concentration of 923 my/1 in 39 to 45 hours.

Although DOC is highly concentrated in foam liquefied water, it has been realized that it is important to always perform adequate and large amount of foam spillover.

On the other hand, turbidity (Δ) of fish tank water
remains constant without increasing during the entire period of the experiment,
This shows that the water purification effect can be obtained by removing bubbles.

This is explained in more detail in Figure 4. From the measurement of the turbidity value of foam liquefied water, if the mud continues to increase without being removed by foam, the turbidity will increase as shown by the dotted line (・). will be 11 degrees in 45 hours. As shown by the solid line (○), the temperature was kept at 2 degrees or less due to bubble removal, indicating the great effect of bubble removal.

- The greatest result discovered in the Rokumoto experiment was the reduction of bacteria, especially pathogenic Vibrio bacteria, by removing the foam, as shown in Figure 5.

General viable bacteria in fish tank water (○) is 3.1 x 103 before the fish mature.
(CFU/d) increased approximately twice as soon as the fish matured, and then increased to 5.4 x 105 after 27 hours, but no further increase was observed even after 48 hours. General viable bacteria in liquefied water (・〉 is 8.7XIQ immediately after adulthood)
What was 5 became 5.9 x 107.4 after 27 hours.
After 8 hours, the amount increased to 7.0×1Q, about 108 orders of magnitude, indicating that the bubbles had a removal effect.

On the other hand, as shown by Δ in Figure 5, Vibrio bacteria, which causes poisoning accidents when eating raw fish, was only detected at extremely low levels in the fish tank water from the start to the end of the experiment; 4.2 after 27 hours from water (see mu in the figure)
XIO3 (CFU/岨, 3.9X10 after 48 hours
'A high concentration of pathogenic Vibrio (CFU/rr11>) was detected.

Analyzing the above test results, it is clear that Vibrio bacteria are more efficiently concentrated into foam, and one of the reasons for this may be that Vibrio bacteria are larger in size. .

Note that the amount of foam generation (speed), expressed as the amount of liquefied water, was on average 210 to 225 af/h. The total amount of water liquefied from the foam was 48% for the initial fish tank water volume (890M>).
It is estimated that the improvement in water quality due to foam separation will be greater by increasing this amount, which is about 1.2% per hour.

On the other hand, immediately after putting the fish in the aquarium or immediately after the transportation vehicle starts running, the fish become stressed, so a lot of secretions are produced by the fish, and a large amount of bubbles are generated, and the bubbles overflow from the Masuda mouth of the bubbles. At other times, it is observed that foam liquefied water does not come out, so it is preferable that the Masuda speed of foam is controlled depending on the situation.

FIG. 6 is an explanatory diagram of the operation of an improved device for removing contaminants such as Vibrio bacteria with a curved aerator, which exemplifies the present invention.

The water tank 19 contains liquid such as aquarium water (including fish) or rice water.

The water in this water tank 19 is passed through a pipe 22 to a foam removal tank 21 by a water suction pump 20 and then to a foam aerator 23.
Water is sent to the upper part.

The force-vous aerator 23 is rotated at high speed in water via a hollow shaft 25 by a motor 24, and emits ultra-micro bubbles 26 radially in a plane (horizontal plane) perpendicular to the descending water flow, so that they mix with the water. The foam absorbs bacteria such as Vibrio bacteria and pollutants contained in the water and floats them to the surface.

It is important for the floating bubbles to float as quietly as possible in order to improve the suction properties of the bubbles.

At this time, the rotational velocity vector of the ultra-fine bubbles 26 generated by the force aerator 23 is detrimental to the stable rise of the bubbles.

Therefore, a partition plate (baffle plate) 27 is placed inside the tank to counteract the rotation of the water.

This action causes the bubbles to rise quietly, and the boundary between the bubbles that collect on the liquid surface and the liquid surface sometimes becomes an emulsion. As a result, not only foam but also water may overflow from the foam overflow port 28, and a large amount of water may enter the tank 29 of the receiver.

To avoid this, it is necessary to carefully maintain the liquid level 30 at an appropriate level relative to the foam overflow port 28.

For this purpose, the liquid level is detected by a small floating body 31 floating on the liquid level 30, and the sensor 33 attached to the upper part of the bar 32, which moves up and down, controls the valve 35 at the outlet 34 of the tank 21 to control the liquid level.

As mentioned above, a major feature of the present invention is that it makes it possible to maintain the liquid level at an optimal height, and also incorporates a control circuit that automatically controls the valve 35 of the outlet 34 to maintain the water level. .

On the other hand, other tests using this device have shown that the higher the water feeding speed, the better the foam is generated, and the water feeding speed is at a speed that is sufficient to circulate the entire amount of water in the foam removal tank 21 in one minute. It has been confirmed that the speed can be increased by 2 to 3 times, and the device of the present invention is considered to be effective not only for transporting live fish but also for treating water containing pollutants such as rice washing water in the food industry.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of an example of a live fish tank equipped with the pollutant removal device of the present invention, Fig. 2 is a perspective view of an example of an aeration device used in the device of the present invention, and Fig. 3 is a live fish tank water using the device of the present invention. water temperature (WT>,
Soluble organic carbon (DOC>, dissolved oxygen concentration (Do),
A graph showing turbidity and changes over time on day 0. Figure 4 shows the turbidity of aquarium water when the device of the present invention is not used, also estimated from the turbidity of aquarium water and the turbidity of foam-liquefied water. FIG. 5 is a graph showing changes over time in the number of general viable bacteria and Vibrio bacteria in live fish tank water and the number of general viable bacteria and Vibrio bacteria in liquefied foam water using the apparatus of the present invention. FIG. 6 is a schematic diagram of another example of the pollutant removal device according to the present invention. Symbols in the figure: 1... Anhydrous tank: 2... Seawater; 3... Sea bream; 4
... Aeration device; 5... Motor: 6... Pump; 7... Foam removal duct; 8... Foam reservoir tank:
9... Foam liquefied water storage tank: 10... Drain valve: 11... Filtration device: 12... Pipe: 13
... Rotation axis: 14 ... Upper disk: 15 ... Lower disk; 16 ... Wing plate; 17 ... Hole: 18 ... Ultra-micro bubble; 19 ... Water tank; 20...Suction pump:
21... Foam removal tank; 22... Pipe; 23.
...Aeration device; 24...Motor; 25...Hollow shaft: 26...Ultra-fine bubbles; 27...Partition plate;
28... Foam overflow outlet; 29... Tank; 30...
・Liquid level: 31...Small floating body: 32...Bar; 3
3...Sensor: 34...Outlet: 35...Valve.

Claims (1)

[Claims] 1) It is characterized by being equipped with a self-suction type foam generating device that generates bubbles by introducing air into the liquid using negative pressure generated on the back surface of a rotating impeller. A device for removing pollutants from liquids. 2) The device for removing contaminants from a liquid according to claim 1, further comprising means for controlling a liquid level position. 3) The device for removing contaminants in a liquid according to claim 1, wherein the liquid flows from the top to the bottom by a rotating impeller. 4) The device for removing contaminants from a liquid according to claim 1, further comprising one or more partition plates for canceling the rotational vector of the bubbles.